Overlay page is the helper view representing as false color view of the first two channels A and B of loaded slide. The next view depicts Overlay Page appearance in Spotfinder.
The default colors are shades of red for channels A image and shades of green for channel B image.
Zoom In and 
Zoom Out buttons can be used for zooming image in and out.
Zoom factor indicator shows the zooming factor relative to the original image scale.
Original image scale is the image view where one screen pixel corresponds to one pixel of displayed image. For instance, the displayed image is twice as less as original 16 bit image in each dimension for Scale factor =2, which is a default settings. All zooming and scrolling actions on this Overlay Page are synchronized for image view on page QC View Page and Analysis Page.